In a typical wireless communications network, a mobile terminal, also known as mobile station, wireless terminal and/or User Equipment unit (UE), communicates via a Radio Access Network (RAN) to a Core Network. The radio access network covers a geographical area, which is divided into cell areas, with each cell area being served by a base station, e.g., a Radio Base Station (RBS). A cell is a geographical area where radio coverage is provided by the radio base station at a base station site. Each cell is identified by an identity within the local radio area, which is broadcast in the cell, and each cell is assigned multiple frequencies. The base stations communicate over the air interface operating on radio frequencies with the mobile terminals within range of the base stations. In other words, radio waves are used to transfer signals between the base station and the mobile terminal. In some cases, a communications network divided into cells may be called cellular systems and the frequencies may be called cellular frequencies.
A mobile terminal comprises an antenna connected to a chassis. The mobile terminals may be mobile stations, user equipments, mobile telephones also known as cellular telephones, laptops with wireless capability. The mobile terminals may also be portable, pocket, hand-held, computer-included, or car-mounted mobile devices, which communicate voice and/or data with a radio access network. The antenna is a necessary feature of the mobile terminal in order to transmit and receive radio signals from e.g., base stations and/or other mobile terminals. A challenge for manufacturers of mobile terminals, chassis and antennas is the interrelationship between cost, size, efficiency and bandwidth.
Coming future mobile terminals need to cover both multi-band and multi-system. Multi-band refers to a device supporting multiple radio frequencies used for communication. A frequency band may be cellular or non-cellular. Examples of cellular bands may be e.g., 700-800 megahertz (MHz), 824-894 MHz, 880-960 MHz, 1710-1850 MHz, 1820-1990 MHz, 1920-2170 MHz, 2300, 2400 and 2500-2700 MHz. In addition, there are non-cellular bands such as Global Positioning System (GPS), Wireless Fidelity (WiFi), Worldwide Interoperability for Microwave Access (Wimax) bands to be covered. Also the antenna has to be compact, less sensitive to user hand and head.
An LC circuit, also called a resonant circuit or tuned circuit, comprises an inductor, represented by the letter L, and a capacitor, represented by the letter C. When connected together, they can act as an electrical resonator storing electrical energy oscillating at the circuit's resonant frequency.